The present invention relates to a catheter placement unit suitable for insertion into the blood system and other body tissue of a patient, and also concerns a placement system for inserting the catheter into a patient and its method of use.
Catheters having a generally elongate axial dimension are utilized in intravenous therapy for a number of purposes including delivery of intravenous liquid and pressure monitoring services. These catheters are normally introduced into the patient's vein at an extremity and threaded to a major vein, or ultimately, to the heart. In this regard, the central venous pressure may be readily measured and monitored with compatible equipment. Introduction of the catheter into the patient generally poses the area of difficulty when using a device of this type.
Prior catheter placement units or systems have used a metal introducer needle for venipuncture purposes and also to provide a passage for the catheter into the venous system. Many prior systems, however, have been designed to leave the introducer needle in position in the patient's vein while the extended catheter is slidably pushed through the needle and then into the patient. Catheter devices of this type are typified in U.S. Pat. Nos. 3,314,427 and 3,055,361. One of the problems associated with this technique is the danger of the catheter, generally made of flexible plastic, being cut or severed as it passes the extremely sharp point on the needle.
Other catheter placement units have been proposed which have recognized the inherent problems of leaving the introducer needle in the patient during catheter use and have therefore provided for removal of the needle. One technique has been to use an introducer catheter with the needle, but without the extended catheter being attached during venipuncture. After venipuncture, the needle is withdrawn, leaving the introducer catheter inserted in the patient's vein. This, of course, introduces another problem, namely, blood escaping from the patient's vein through the intravenous catheter. Accordingly, these catheter placement devices have had to provide some means of preventing the escape of blood, either by using a seal on the catheter device or the application of digital pressure above the insertion site, or some combination thereof. As soon as the introducer needle is withdrawn, the catheter is then generally connected to the introducer catheter whereupon it is slidably inserted through the catheter and then into the patient's vein. Devices of this type are typified in U.S. Pat. Nos. 3,825,001 and 3,757,771. It can be seen, that these type catheter units which provide for the removal for the needle are not "closed systems." In other words, the catheter is not attached to the introducer needle-introducer catheter combination upon original insertion into the patient; such attachment is only made after the needle is withdrawn. Accordingly, the need for further improvements is recognized in the utilization of catheter placement units and their introduction into a patient.